1. Field of the Invention
This invention relates generally to printers and copiers and the like, and more particularly, relates to adjustments by such devices in response to variations in print media characteristics.
2. State of the Art
A myriad of document processing devices have been developed, including printers, photocopy machines, scanners, as well as other devices that either create images and patterns on print media (e.g., printers) or analyze images and patterns already resident on media (e.g., scanners). Complications arise in the use of these devices when media, having variations in media characteristics, are used. For example, printers may be presented with a myriad of print media, such as paper, which exhibit variations in thickness and stiffness and requires individualized image processing parameters in order to create an acceptable image on the specific print media. Without such image processing adaptation, the print quality may become unacceptable and may even result in damage to the processing device.
Insight into the media characteristic of the media being acted upon by a document processing device enables the device to adapt and provide improved processing services to the media. For example, thicker media may require alternative handling such as alterations to forces associated with the xe2x80x9cpickxe2x80x9d or lifting forces for removing the media from a document processing device storage tray. Furthermore, document processing device attachments such as duplexers or output bins also have specifications including a range of media characteristics compatible with the attachment devices. Yet another concern of document processing devices, particularly printers and copiers, results from the variations in fuser temperature profiles as a function of the media thickness. Therefore, it would be advantageous to determine media characteristics such as thickness and stiffness of the media in order to more advantageously alter document processing device parameters.
In yet another printing process, namely the application of toner to the print media, it should be appreciated that the thicker the print media, the more electrical charge must be applied to the media in order to attract an adequate amount of toner. Therefore, there is a need for providing an improved sensor capable of real or near real-time media evaluation to quantify the media characteristics allowing the document processing device to adjust the performance of the device""s imaging processes.
Mechanical media thickness measurement devices are known in the art. One type of mechanical thickness sensor uses a mechanical arm assembly coupled to a measurement circuit. The mechanical arm engages the surface of the media under evaluation. The measurement circuit measures the displacement of the media or the mechanical arm and generates a signal indicative of the media thickness. The present invention provides an alternative to mechanical techniques for detecting the thickness of print media.
The present invention is directed to a fiber optic media thickness sensor used in a print media or document processing device. The invention is further directed to a method for measuring media thickness in a media processing device using a fiber optic sensor.